JP5186082B2 - Granulation method and granulated product of soft polyolefin resin - Google Patents

Description

  The present invention relates to a method for granulating a soft polyolefin resin. More specifically, the present invention relates to a granulation method that can reduce stickiness of a soft polyolefin resin and prevent blocking of the granulated product. Furthermore, the present invention relates to a granulation method capable of preventing re-fusion of granulated products after granulation.

Soft polyolefin resin is widely used as a raw material for films and the like as a substitute for a soft vinyl chloride resin having a large environmental load.
Since the soft polyolefin-based resin contains a large amount of low molecular weight components due to its properties, the surface of the granulated product may exhibit adhesiveness. For this reason, when the polymerized soft polyolefin resin is granulated to a size that is easy to handle as a product, there is a problem that the granulated materials stick to each other and easily form a block (blocking). Moreover, even after granulation, there is a problem that re-fusion between the granulated materials is likely to occur.

As a granulation method of the soft polyolefin, for example, the resin is extruded from an extrusion die having a plurality of downward outlets toward a cooling water tank below, and is cut into pellets by cutting with a rotary cutter on the lower surface of the die outlet. A method of spraying release agent-containing cooling water from below is disclosed for the pellets immediately after being cut (see, for example, Patent Document 1).
However, this method requires the use of a specific resin composition or the application of a release agent to the surface of the granulated product. Moreover, in the cooling process after granulation, since the pellet floated on the water surface, the cooling efficiency was low.

  The inventors of the present invention have found that, after heating and melting a soft polyolefin-based resin, cooling to the melting point or lower, stirring and kneading and then granulating, the adhesiveness of the resulting granulated product can be reduced. An application has been filed (Patent Document 2).

JP-A-7-88839 JP 2005-179556 A

However, in the method of Patent Document 2, since the resin after polymerization was cooled and then melted again, the productivity was poor and there was room for further improvement. In addition, expensive equipment such as a kneader is required to stir and knead while cooling after melting the resin. Furthermore, depending on the granulation method, the pellet floats in the cooling water tank, so that the cooling efficiency is low. For this reason, the further improvement was calculated | required from the request | requirement of productivity improvement of a granulated material.
In view of the above problems, an object of the present invention is to provide a method for efficiently granulating a soft polyolefin resin.
Another object of the present invention is to provide an efficient granulation method in which re-fusion between granulated materials does not occur even after granulation.

In order to solve this problem, the present inventors have intensively studied. As a result, the molten soft polyolefin resin after polymerization and devolatilization is cooled to a certain temperature, and then granulated by an underwater granulation method. Thus, it was found that the adhesiveness of the resin can be reduced, and cooling can be improved when the resin is transferred to the post-granulation step (dehydration step).
Furthermore, the present inventors have also found that re-fusion of granulated products can be suppressed by subjecting the soft polyolefin resin obtained in the granulating step to a retention treatment for a specific time in a specific temperature range, thereby completing the present invention.

According to the present invention, the following granulating method and granulated product of a flexible polyolefin resin are provided.
1. The step of cooling the soft polyolefin resin melted by the devolatilization step after polymerization to a temperature range of the melting point (Tm-D) ± 50 ° C. of the resin and the cooled resin are formed by an underwater granulation method. A granulation method of a soft polyolefin resin, comprising a step of granulating, wherein a temperature of cooling water in the underwater granulation method is 30 ° C. or less, and an anti-fusing agent is added to the cooling water.
2. 2. The method for granulating a soft polyolefin resin as described in 1 above, wherein the soft polyolefin resin is obtained by polymerizing an α-olefin having 3 to 20 carbon atoms using a metallocene catalyst.
3. The granulation method of the soft polyolefin resin according to 1 or 2, wherein the soft polyolefin resin is polypropylene having the following characteristics (1) to (3).
(1) Melting point (Tm-D) is 20 to 120 ° C
(2) Crystallization time is 3 minutes or more (3) PP stereoregularity index [mm] is 50 to 90 mol%
4). The granulation method of the soft polyolefin resin according to 1 or 2 above, wherein the soft polyolefin resin is a 1-butene polymer having the following property (4).
(4) PB stereoregularity index {(mmmm) / (mmrr + rmmr)} is 20 or less. The granulation method of the soft polyolefin resin according to any one of 1 to 4 above, wherein after the granulation step, the soft polyolefin resin is subjected to a residence treatment at a temperature of 50 ° C. or less and a time of 5 minutes to 24 hours. .
6). 6. The method for granulating a soft polyolefin resin as described in 5 above, wherein the retention treatment is performed using a water tank.
7). The soft polyolefin resin granulated material granulated by the granulation method in any one of said 1-6.

In the granulation method of the soft polyolefin resin of the present invention, the heat in the devolatilization step is effectively used, and since the underwater granulation method with high cooling efficiency is used, the productivity is high. Moreover, since the cooling efficiency at the time of granulation is high, the size of the equipment can be reduced.
Furthermore, according to the granulation method of the soft polyolefin-based resin of the present invention, the utility value of the product is improved by preventing re-fusion of the granulated products after granulation.

Hereinafter, the granulation method of the present invention will be specifically described.
FIG. 1 is a flowchart for explaining the granulation method of the present invention.
The raw material olefin monomer is polymerized by a conventional method such as a solution polymerization method or a gas phase polymerization method to become a soft polyolefin resin. In order to remove a solvent, unreacted monomer components, and the like from this resin, heating and devolatilization are performed. Since the temperature of the devolatilization step is usually about 100 ° C. to 250 ° C., the resin is in a molten state. In the present invention, this molten resin is directly transferred to the cooling step. This eliminates the need for a resin reheating step, thereby improving production efficiency.
In addition, a devolatilization process can be implemented with apparatuses, such as a normal melting tank. Moreover, the molten resin can be transferred through a pipe line using a transfer means such as a gear pump.

In the present invention, the melted soft polyolefin-based resin is granulated after cooling to the temperature range of the melting point (Tm-D) ± 50 ° C. of the resin, preferably to the temperature range of the melting point (Tm-D) ± 20 ° C. To do. Thereby, the adhesiveness of resin at the time of granulation can be reduced. Therefore, it can suppress that a pellet adheres and forms a lump at the time of granulation.
In the present specification, the melting point (Tm-D) of the resin is determined by using a differential scanning calorimeter (DSC), holding a 10 mg sample at 10 ° C. for 5 minutes in a nitrogen atmosphere at 10 ° C./min. It is defined as the peak top of the peak observed on the highest temperature side of the melting endothermic curve obtained by raising the temperature.

  As a device for cooling the resin, a polymer cooler, a jacketed kneader, a jacketed polymer mixer, or the like can be used. A polymer cooler is preferred because it is relatively inexpensive and can reduce equipment costs.

After cooling the resin, granulation in water is performed. The underwater granulation method will be described with reference to the drawings.
FIG. 2 is a schematic diagram for explaining the underwater granulation method.
In the underwater granulation method, the resin cooled by the cooler 11 passes through a die 12 attached to the tip of the cooler 11 and has one or more holes having a predetermined shape, and is then cut in a cutting chamber 13 to form a pellet. It becomes.

In the cutting chamber 13, the cutter blade rotates at high speed to cut the resin. The cooling water in the chamber 13 circulates through the chamber 13, the dehydrator 14 and the cooling water tank 15, and the cut pellets are conveyed from the chamber 13 to the dehydrator 14 by the circulating water flow. And pellet resin and cooling water are isolate | separated by the dehydrator 14, and a pellet is collect | recovered.
By adopting the underwater granulation method, the pellets do not float on the water surface unlike the cooling water tank, and the cut resin pellets are efficiently cooled by the water flow, so that the cooling equipment can be downsized.

In this invention, the temperature of the cooling water in an underwater granulation method shall be 30 degrees C or less. Preferably, it is 20 degrees C or less, More preferably, it is 15 degrees C or less. When the temperature of the cooling water is higher than 30 ° C., cooling of the resin at the time of granulation becomes insufficient, so that there is a possibility that the pellets are combined to form a lump.
The temperature of the cooling water can be adjusted by heating and cooling with a heat medium cooler or a heat medium heater (not shown).

An anti-fusing agent is added to the cooling water. Silicone or the like can be used as the anti-fusing agent.
The addition amount of the anti-fusing agent is appropriately adjusted depending on the type of anti-fusing agent used. For example, when silicone is used, 100 wt ppm to 5000 wt ppm in cooling water, preferably 500 wt ppm. Add ~ 1000 ppm by weight.

  The peripheral speed of the cutter blade in the cutting chamber is usually 1 to 20 m / s and preferably 1 to 10 m / s.

  The soft polyolefin resin to which the granulation method of the present invention can be applied is not particularly limited, but is particularly preferably applicable to a polymer obtained by polymerizing an α-olefin having 3 to 20 carbon atoms using a metallocene catalyst. This is because a polymer polymerized using a metallocene catalyst has a uniform molecular weight and composition distribution, so that there are very few components that induce crystal nuclei and fluidity even when cooled by a cooler.

  Examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-octene Examples include eicosen. The soft polyolefin resin may be a homopolymer of these α-olefins or a copolymer. In the case of a copolymer, ethylene may be contained in addition to the α-olefin. A propylene polymer and a 1-butene polymer are preferable.

Metallocene-based soft polyolefin resin is a compound that forms an ionic complex by reacting with a transition metal compound belonging to Group 4 of the periodic table and methylaluminoxane or a transition metal compound belonging to Group 4 of the periodic table having a cyclopentadienyl ring In the presence of a metallocene catalyst composed of an organoaluminum compound, the α-olefin can be polymerized.
The transition metal compound of Group 4 of the periodic table having a cyclopentadienyl ring as the main catalyst includes a cycloalkadienyl group or a substituted product thereof, specifically, an indenyl group, a substituted indenyl group and a partial hydride thereof. Zirconium, titanium, and hafnium compounds having a multidentate coordination compound in which at least two groups selected from the group consisting of these groups bonded via a lower alkylene group or a silylene group are used.

  For example, transition metal compounds are H.264. H. Brintzinger et al, J. MoI. Organometal. Chem. , 288, 63 (1985), ethylene-bis- (indenyl) zirconium dichloride; Am. Chem. Soc. , 109, 6544 (1987), ethylene-bis- (indenyl) hafnium dichloride; Dimethylsilylbis (2,4-dimethylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (2,4,5-trimethylcyclopentadienyl) zirconium dichloride described in Yamazaki et al, Chemistry Letters, 1853 (1989) or There are sterically rigid chiral compounds of zirconium and hafnium compounds such as hafnium dichloride of these complexes.

  Specifically, ethylene bis (indenyl) zirconium dichloride, ethylene bis (4,5,6,7-tetrahydro-1-indenyl) zirconium dichloride, ethylene bis (4-methyl-1-indenyl) zirconium dichloride, ethylene Bis (5-methyl-1-indenyl) zirconium dichloride, ethylenebis (6-methyl-1-indenyl) zirconium dichloride, ethylenebis (7-methyl-1-indenyl) zirconium dichloride, ethylenebis (2,3-dimethyl- 1-indenyl) zirconium dichloride, ethylene bis (4,7-dimethyl-1-indenyl) zirconium dichloride, ethylene bis (indenyl) hafnium dichloride, ethylene bis (4,5,6,7-tetrahydro-1-indeni ) Hafnium dichloride, ethylene bis (4-methyl-1-indenyl) hafnium dichloride, ethylene bis (5-methyl-1-indenyl) hafnium dichloride, ethylene bis (6-methyl-1-indenyl) hafnium dichloride, ethylene bis (7 -Methyl-1-indenyl) hafnium dichloride, ethylenebis (2,3-dimethyl-1-indenyl) hafnium dichloride, ethylenebis (4,7-dimethyl-1-indenyl) hafnium dichloride, dimethylsilylenebis (indenyl) zirconium dichloride Dimethylsilylene bis (indenyl) hafnium dichloride, dimethylsilylene bis (4-methylindenyl) zirconium dichloride, dimethylsilylene bis (indenyl) hafnium dichloride, dimethyl Silylene bis (2,4,5-trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylene bis (2,4,5-trimethylcyclopentadienyl) hafnium dichloride, dimethylsilylene bis (2,4-dimethylcyclopentadienyl) Zirconium dichloride, dimethylsilylene bis (2,4-dimethylcyclopentadienyl) hafnium dichloride, dimethylsilylene bis (3-methylcyclopentadienyl) zirconium dichloride, dimethylsilylene bis (3-methylcyclopentadienyl) hafnium dichloride, Examples thereof include dimethylsilylene bis (2-methyl-4-phenylindenyl) zirconium dichloride, dimethylsilylene bis (benzoindenyl) zirconium dichloride, and the like.

  (Dimethylsilylene) (dimethylsilylene) -bis (indenyl) zirconium dichloride, (ethylene) (ethylene) -bis (indenyl) zirconium dichloride, (ethylene) (ethylene) -bis (3-methylindenyl) zirconium dichloride, (Ethylene) (ethylene) -bis (4,7-dimethylindenyl) zirconium dichloride and the like, and those obtained by replacing zirconium in these compounds with hafnium or titanium.

  Compounds that react with the transition metal compounds of Group 4 of the periodic table of the cocatalyst to form ionic complexes include triphenylcarbinium tetrakis (pentafluorophenyl) borate, N, N-dimethylanilinium tetrakis (penta Tetra (pentafluorophenyl) borate anion-containing compounds such as fluorophenyl) borate and lithium tetrakis (pentafluorophenyl) borate, triphenylcarbinium tetrakis (pentafluorophenyl) aluminate, N, N-dimethylanilinium tetrakis ( Tetra (pentafluorophenyl) aluminate anion-containing compounds such as pentafluorophenyl) aluminate and lithium tetrakis (pentafluorophenyl) aluminate are preferably used.

  The organoaluminum compound has at least one Al—C bond in the molecule. Specific examples of such organoaluminum compounds include trialkylaluminum such as triethylaluminum, triisobutylaluminum and trihexylaluminum, dialkylaluminum halide such as diethylaluminum halide and diisobutylaluminum halide, a mixture of trialkylaluminum and dialkylaluminum halide, tetraethyl Examples thereof include alkylalumoxanes such as dialumoxane and tetrabutylalumoxane. Among these organoaluminum compounds, trialkylaluminum, a mixture of trialkylaluminum and dialkylaluminum halide, and alkylalumoxane are preferable, and triethylaluminum, triisobutylaluminum, a mixture of triethylaluminum and diethylaluminum chloride, and tetraethyldialumoxane are particularly preferable. preferable. As the organic aluminum, triethylaluminum, triisobutylaluminum or the like is preferably used. These metallocene catalysts and / or promoters may be supported and used, and examples of the carrier include organic compounds such as polystyrene and inorganic oxides such as silica and alumina.

As a polymerization method, any method such as a bulk polymerization method, a solution polymerization method, a gas phase polymerization method, and a suspension polymerization method may be used, and either a batch method or a continuous method may be used.
In addition, preliminary polymerization may be performed in advance with a small amount of α-olefin, such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, and the like. The polymerization temperature is usually in the range of −50 to 250 ° C., preferably 0 to 150 ° C., the polymerization time is usually in the range of 1 to 10 hours, and the pressure is usually normal pressure to 300 kg / cm ² -G. Range.

The granulation method of the present invention is particularly preferably applicable to a soft polypropylene resin having the following characteristics.
(1) Melting point (Tm-D) is 20 to 120 ° C
(2) Crystallization time is 3 minutes or more (3) PP stereoregularity index [mm] is 50 to 90 mol%

  If the melting point (Tm-D) is less than 20 ° C, handling at room temperature may be difficult, and if it exceeds 120 ° C, the effects of the present invention may not be obtained efficiently. Melting | fusing point (Tm-D) becomes like this. Preferably it is 50-100 degreeC, More preferably, it is 60-90 degreeC.

The crystallization time is preferably 3 minutes or longer. This is because if the crystallization time is less than 3 minutes, the effect of promoting crystallization is small.
The crystallization time is preferably 5 minutes or more, more preferably 10 minutes or more, since the effect of promoting crystallization becomes remarkable.
The crystallization time was measured by using a differential scanning calorimeter, and the sample was melted at 190 ° C. for 3 minutes in a nitrogen atmosphere, and then liquefied nitrogen was introduced and rapidly (about 300 ° C./min) up to 25 ° C. It means the time from when the temperature is lowered and held at this temperature and the sample temperature reaches 25 ° C. until the crystallization exothermic peak is observed.

Such a soft polypropylene resin becomes supercooled even if the temperature falls below the melting point, and does not lose fluidity (it does not easily crystallize even if it falls below the crystallization temperature). For this reason, even when the temperature is below the melting point, the fluid state is maintained in the cooler, and when it is extruded from the cooler, it is crystallized for the first time.
In addition, melting | fusing point (Tm-D) and crystallization time of a soft polypropylene resin can be controlled by adjusting the stereoregularity index mentioned later.

The PP stereoregularity index [mm] of the soft polypropylene resin is preferably 50 to 90 mol% polypropylene.
If it is less than 50 mol%, stickiness may occur, and if it exceeds 90 mol%, the workability may decrease. Preferably it is 50-80 mol%, More preferably, it is 60-80 mol%.
In the present invention, the PP stereoregularity index [mm] is a value determined in accordance with the method proposed in “Macromolecules, 6925 (1973)” reported by A. Zambelli et al. means.

The flexible polyolefin resin is preferably a 1-butene polymer having a PB stereoregularity index {(mmmm) / (mmrr + rmmr)} of 20 or less. When the PB stereoregularity index exceeds 20, a decrease in flexibility and a decrease in workability occur.
The 1-butene polymer preferably has the following properties (1) and (2) as in the case of the polypropylene described above.
(1) Melting point (Tm-D) is 20 to 120 ° C
(2) Crystallization time is 3 minutes or more Furthermore, it is preferable that the 1-butene polymer has the following property (4).
(4) PB stereoregularity index {(mmmm) / (mmrr + rmmr)} is 20 or less

In the present invention, the PB stereoregularity index {(mmmm) / (mmrr + rmmr)} is calculated according to “Polymer Journal, 16, 717 (1984)”, J. Asakura et al. “Macromol. Chem. Phys., C29, 201 (1989)” reported by Randall et al. Based on the method described in “Macromol. Chem. Phys., 198, 1257 (1997)” reported by Busico et al., The mesopentad fraction (mmmm) and abnormal insertion content (1,4 insertion fraction) were obtained. , PB stereoregularity index {(mmmm) / (mmrr + rmmr)} is calculated. That is, the signals of methylene group and methine group were measured using ¹³ C nuclear magnetic resonance spectrum to determine the mesopentad fraction and abnormal insertion content in the poly (1-butene) molecule, and the PB stereoregularity index {(mmmm ) / (Mmrr + rmmr)}.

  The PP stereoregularity index [mm] and the PB stereoregularity index {(mmmm) / (mmrr + rmmr)} can be controlled by adjusting the type of catalyst and adjusting the polymerization temperature and the monomer concentration during the polymerization process.

It is preferable that the granulated product of the soft polyolefin resin is retained at a predetermined temperature for a predetermined period after the granulation step of the soft polyolefin resin. By providing this step, it is possible to prevent re-fusion of the granulated products generated after granulation.
As a facility for retaining the granulated material, a general tank, piping, or the like can be used. When a tank is used, a large surface area is desirable in order to prevent fusion of the granulated products floating on the tank surface. It is also desirable to carry out stirring to enhance the cooling effect. In order to prevent a short pass, it is also effective to connect the tanks in series to prevent re-fusion of the granulated product. When piping is used, it is desirable that the piping has a length sufficient to earn a predetermined residence time. If a long pipe interferes with the layout in the apparatus, the pipe may be wound in a coil shape or bundled in a bundle shape. Furthermore, in order to adjust both the tank and the piping to the optimum temperature at which crystallization is promoted, it is desirable to have a temperature adjustment mechanism. As the retention facility, a water tank is preferable from the viewpoint of cost and the like.
As a medium to be used for retaining the granulated material, air, nitrogen and other gases can be used in addition to water which is industrially easy to handle. When water is used, an anti-fusing agent may be added.

  The residence time is desirably 5 minutes or more and 24 hours or less as the time required for the crystallization to sufficiently proceed. If it is 5 minutes or less, crystallization may be insufficient, and the crystallization of the resin is sufficiently advanced up to 24 hours, and if the residence time is longer than that, the equipment becomes uselessly large. It leads to cost increase and is not desirable.

  For example, the temperature of water in the case of using a water tank is set to 0 ° C. or more and 50 ° C. or less as a temperature at which crystallization proceeds rapidly. If it is 0 ° C. or lower, it is unsuitable because it freezes, and if it is 50 ° C. or higher, it is not desirable because the crystallization rate is slow.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.
The physical properties of the polymerized resin were measured by the following method.
(1) Molecular weight (Mw) and molecular weight distribution (Mw / Mn)
It measured with the following apparatus and conditions, and computed from the mass average molecular weight Mw and the number average molecular weight Mn.
GPC measurement device Column: TOSO GMHHR-H (S) HT
Detector: RI detector for liquid chromatogram WATERS 150C measurement conditions Solvent: 1,2,4-trichlorobenzene Measurement temperature: 145 ° C
Flow rate: 1.0 ml / min Sample concentration: 2.2 mg / ml Injection volume: 160 microliter Calibration curve: Universal Calibration
Analysis program: HT-GPC (Ver.1.0)

(2) PP stereoregularity index [mm] and PB stereoregularity index {(mmmm) / (mmrr + rmmr)}
It was measured by the method described above. The ¹³ C nuclear magnetic resonance spectrum was measured using the following apparatus and conditions.
Apparatus: JNM-EX400 type ¹³ C-NMR apparatus manufactured by JEOL Ltd. Method: Proton complete decoupling method Concentration: 230 mg / ml Solvent: 90:10 (volume ratio) of 1,2,4-trichlorobenzene and heavy benzene Mixed solvent temperature: 130 ° C
Pulse width: 45 °
Pulse repetition time: 4 seconds Integration: 10,000 times

(3) Glass transition temperature (Tg), melting point (Tm-D), and crystallization time Using a differential scanning calorimeter (DSC: DSC-7, manufactured by Perkin Elmer Co.), the glass transition temperature (Tg) was measured by the method described above.

Production Example Synthesis of metallocene catalyst [(1,2′-dimethylsilylene) (2,1′-dimethylsilylene) -bis (3-trimethylsilylmethylindenyl) zirconium dichloride] in a Schlenk bottle (1,2′-dimethylsilylene) 3.0 g (6.97 mmol) of a lithium salt of (2,1′-dimethylsilylene) -bis (indene) was dissolved in 50 mL of THF and cooled to −78 ° C. 2.1 mL (14.2 mmol) of iodomethyltrimethylsilane was slowly added dropwise and stirred at room temperature for 12 hours. The solvent was distilled off, 50 mL of ether was added, and the mixture was washed with a saturated ammonium chloride solution. After liquid separation, the organic phase was dried to remove the solvent, and 3.04 g (5.88 mmol) of (1,2′-dimethylsilylene) (2,1′-dimethylsilylene) -bis (3-trimethylsilylmethylindene) Obtained (yield 84%).

Next, 3.04 g (5.88 mmol) of (1,2'-dimethylsilylene) (2,1'-dimethylsilylene) -bis (3-trimethylsilylmethylindene) obtained above in a Schlenk bottle under a nitrogen stream. ) And 50 mL of ether. After cooling to −78 ° C. and adding 7.6 mL (11.7 mmol) of n-BuLi (hexane solution 1.54 M), the mixture was stirred at room temperature for 12 hours. The solvent was distilled off, and the resulting solid was washed with 40 mL of hexane to obtain 3.06 g (5.07 mmol) of the lithium salt as an ether adduct. (Yield 73%)
The result of the measurement by ¹ H-NMR (90 MHz, THF-d ₈ ) is shown.
δ: 0.04 (s, 18H, trimethylsilyl), 0.48 (s, 12H, dimethylsilylene), 1.10 (t, 6H, methyl), 2.59 (s, 4H, methylene), 3.38 (Q, 4H, methylene), 6.2-7.7 (m, 8H, Ar-H)

The lithium salt obtained above was dissolved in 50 mL of toluene under a nitrogen stream. After cooling to -78 ° C, a suspension of 1.2 g (5.1 mmol) of zirconium tetrachloride, which had been cooled to -78 ° C in advance, in toluene (20 mL) was added dropwise. After dropping, the mixture was stirred at room temperature for 6 hours, and then the solvent of the reaction solution was distilled off. The obtained residue was recrystallized from dichloromethane to obtain 0.9 g (1. 1'-dimethylsilylene) (2,1'-dimethylsilylene) -bis (3-trimethylsilylmethylindenyl) zirconium dichloride. 33 mmol). (Yield 26%)
The result of the measurement by ¹ H-NMR (90 MHz, CDCl ₃ ) is shown.
δ: 0.0 (s, 18H, trimethylsilyl), 1.02, 1.12 (s, 12H, dimethylsilylene), 2.51 (dd, 4H, methylene), 7.1-7.6 (m, 8H, Ar-H)

Example 1
(1) Polymerization of propylene In a stainless steel reactor with a stirrer and an internal volume of 0.20 m ³ , 30 L / h of n-heptane, 15 mmol / h of triisobutylaluminum (manufactured by Nippon Alkyl Aluminum), methylaluminoxane (Albemarle) 15 mmol / h, and (1,2′-dimethylsilylene) (2,1′-dimethylsilylene) -bis (3-trimethylsilylmethylindenyl) zirconium chloride obtained in Preparation Example at 15 μmol / h. Supplied. Propylene and hydrogen were continuously supplied at a polymerization temperature of 60 ° C. so that the gas phase hydrogen concentration was 50 mol% and the total pressure in the reactor was maintained at 0.7 MPaG, to polymerize polypropylene.

(2) Granulation of polypropylene Irganox 1010 was added to the obtained polymerization solution to 500 ppm by weight, and the solvent was removed at an internal temperature of 150 ° C. using a stainless devolatilization tank with an internal volume of 3 m ^3. did.
Thereafter, the molten resin was transferred to a polymer mixer with jacket (L84-VPR-3.7, manufactured by Satake Corporation) with a transfer pump. After cooling the resin to 65 ° C. with a polymer mixer, it was granulated in water with a granulator. As the granulator, PASC-21HS manufactured by Tanabe Plastics Machine Co., Ltd. was used, the cooling water temperature was 10 ° C., and the peripheral speed of the cutter was 3.8 m / s. Moreover, silicone (Shin-Etsu Chemical Co., Ltd., X-22-904) was added to cooling water so that it might become 600 weight ppm.

As a result of granulation in water, the polypropylene pellets did not stick to each other in the granulation step and did not form a lump.
When the obtained metallocene polypropylene was evaluated, the molecular weight distribution (Mw / Mn) was 1.8, the molecular weight (Mw) was 33,000, the PP stereoregularity index [mm] was 67 mol%, and the glass transition temperature ( Tg) was −4 ° C., and the melting point (Tm-D) was 70 ° C. The crystallization time was 6 minutes.

Comparative Example 1
The operation was carried out in the same manner as in Example 1 except that the resin was not cooled by the polymer mixer and the temperature of the polypropylene resin at the outlet was 150 ° C.
As a result, the polypropylene pellets adhered to each other in the granulation process, and grew into a lump in the granulation process.

Comparative Example 2
The operation was carried out in the same manner as in Example 1 except that no silicone was added.
As a result, the polypropylene pellets adhered to each other in the granulation process, and grew into a lump in the granulation process.

Comparative Example 3
The operation was performed in the same manner as in Example 1 except that the cooling water temperature was 40 ° C.
As a result, the polypropylene pellets adhered to each other in the granulation process, and grew into a lump in the granulation process.

Example 2
(1) Polymerization of butene-1 In a stainless steel reactor with an agitator and an internal volume of 0.20 m ³ , n-heptane was 20 L / h, triisobutylaluminum (manufactured by Nippon Alkyl Aluminum) was 16 mmol / h, methylaluminoxane ( Albemarle) (17 mmol / h), and (1,2′-dimethylsilylene) (2,1′-dimethylsilylene) -bis (3-trimethylsilylmethylindenyl) zirconium chloride obtained in the above production example was added at 17 μmol / h. h was fed continuously. Polybutene-1 was polymerized by continuously supplying 1-butene and hydrogen so that the gas phase hydrogen concentration was 50 mol% at a polymerization temperature of 60 ° C. and the total pressure in the reactor was maintained at 0.7 MPaG.

(2) Granulation of polybutene-1 Irganox 1010 was added to the obtained polymerization solution to 500 ppm by weight, and the solvent was removed at an internal temperature of 150 ° C. using a stainless devolatilization tank with an internal volume of 3 m ^3. Carried out. Thereafter, polybutene-1 was granulated in the same manner as in Example 1.
As a result of granulation in water, the polybutene-1 pellets did not stick to each other in the granulation step and did not form a lump.

  When the obtained metallocene polybutene-1 was evaluated, the molecular weight distribution (Mw / Mn) was 1.8, the molecular weight (Mw) was 70,000, and the PB stereoregularity index {(mmmm) / (mmrr + rmmr)} The glass transition temperature (Tg) was -29 ° C, and the melting point (Tm-D) was 71 ° C. The crystallization time was 30 minutes or more.

Example 3
The pellet obtained in Example 1 was received in a water bath having a water temperature of 13 ° C. and allowed to stay for 40 minutes, and then the pellet was taken out from the water bath, and the following refusion evaluation experiment was performed.
Put the pellets taken out of the water tank into a cell with a cross-sectional area of 60 mm x 60 mm and height 70 mm, put a 330 g lid on the top, and place a 5,000 g weight on it, and keep it at a constant temperature of 50 ° C. Left for 90 minutes.
After 90 minutes, the weight was removed, the lid was removed, and the re-fusion state of the pellets was visually confirmed. As a result, re-fusion between the pellets was not confirmed.

Comparative Example 4
The same operation as in Example 3 was performed except that the residence time in the water tank was 3 minutes. As a result, re-fusion of pellets occurred.

Comparative Example 5
The same operation as in Example 3 was performed except that the water temperature of the water tank was 80 ° C. As a result, re-fusion of pellets occurred.

Example 4
The pellet obtained in Example 2 was received in a water bath having a water temperature of 13 ° C. and retained for 40 minutes, and then the pellet was taken out from the water bath, and the following re-fusion evaluation experiment was performed.
Put the pellets taken out from the water tank into a cell with a cross-sectional area of 60 mm x 60 mm and a height of 70 mm, put a 330 g lid on the top surface, put a 5,000 g weight on it, and keep it at a constant temperature of 50 ° C. And left for 90 minutes.
After 90 minutes, the weight was removed, the lid was removed, and the re-fusion state of the pellets was visually confirmed. As a result, re-fusion between the pellets was not confirmed.

ADVANTAGE OF THE INVENTION According to this invention, the granulation method of soft polyolefin resin with high productivity can be provided by using the heat | fever of a devolatilization process effectively, and using the underwater granulation method with high cooling efficiency. .
ADVANTAGE OF THE INVENTION According to this invention, the granulation method of the efficient flexible polyolefin resin which does not produce re-fusion can be provided.

It is a flowchart for demonstrating the granulation method of this invention. It is a schematic diagram for demonstrating an underwater granulation method.

Explanation of symbols

11 Cooling machine 12 Dies 13 Cutting chamber 14 Dehydrator 15 Cooling water tank

Claims (6)

A step of cooling a soft polyolefin-based resin in a molten state by a devolatilization step after polymerization to a temperature range of a melting point (Tm-D) ± 50 ° C. of the resin;
A step of granulating the cooled resin by an underwater granulation method,
The temperature of the cooling water in the underwater granulation method is 30 ° C. or less, and an anti-fusing agent is added to this cooling water ,
After the granulation step, the soft polyolefin resin is further subjected to a residence treatment at a temperature of 50 ° C. or less and a time of 5 minutes or more and 24 hours or less,
A method for granulating a soft polyolefin resin, wherein the soft polyolefin resin is a polypropylene or 1-butene polymer having a crystallization time of 3 minutes or more . The soft polyolefin resin, propylene or 1-butene, granulating the method of flexible polyolefin resin according to claim 1 is obtained by polymerization using a main Tarosen catalyst. The method for granulating a soft polyolefin resin according to claim 1 or 2, wherein the polypropylene has a melting point (Tm-D) of 20 to 120 ° C and a PP stereoregularity index [mm] of 50 to 90 mol% . The granulation method of the soft polyolefin resin according to claim 1 or 2, wherein the PB stereoregularity index {(mmmm) / (mmrr + rmmr)} of the 1-butene polymer is 20 or less . The granulation method of the soft polyolefin-type resin in any one of Claims 1-4 which performs the said residence process using a water tank. The soft polyolefin resin granulated material granulated by the granulation method in any one of Claims 1-5 .

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